A short synthesis of the postulated structure for indolizidine alkaloid 259B with the hydrogens at C5 and C9 entgegen has been achieved with complete control of stereochemistry at C5. Both diastereoisomers at C8 were obtained, but neither proved to be the natural product. The comparison of the mass and FTIR spectral properties of the synthetic compounds to those of the natural material strongly...

Average configuration-dependent physical properties have been evaluated for tri-, tetra-, and hexafunctional polymethylene stars perturbed by electrostatic repulsion of charges placed at the free chain ends. Configuration-dependent properties evaluated were the probability for a trans placement, expansion of (sl), the mean-square radius of gyration, asymmetry of the distribution of chain atoms,...

Bayesian inference is a popular and widely-used approach to infer phylogenies (evolutionary trees). However, despite decades of widespread application, it remains difficult judge how well given Markov chain Monte Carlo (MCMC) run explores the space phylogenetic trees. In this paper, we investigate error phylogenies, focusing on high-dimensional summaries posterior distribution, including variab...

Statistical properties of the bootstrap test of interior branch lengths of phylogenetic trees have been studied and compared with those of the standard interior-branch test in computer simulations. Examination of the properties of the tests under the null hypothesis showed that both tests for an interior branch of a predetermined topology are quite reliable when the distribution of the branch l...

With being listed in the Stockholm Convention, ban on short-chain chlorinated paraffins (SCCPs) has been put agenda China. Based literature over past decade, this study comprehensively analyzed occurrence, distribution of and human exposure to SCCPs China, aiming provide a reference for changes after ban. were ubiquitous environmental matrices, levels considerably higher than those other countr...

Markov chain Monte Carlo is an umbrella term for algorithms that use Markov chains to sample from a given probability distribution. This paper is a brief examination of Markov chain Monte Carlo and its usage. We begin by discussing Markov chains and the ergodicity, convergence, and reversibility thereof before proceeding to a short overview of Markov chain Monte Carlo and the use of mixing time...

The advances in variational inference are providing promising paths Bayesian estimation problems. These make phylogenetic an alternative approach to Markov Chain Monte Carlo methods for approximating the posterior. However, one of main drawbacks such approaches is modelling prior through fixed distributions, which could bias posterior approximation if they distant from current data distribution...

Background Short-chain PFASs (per- and polyfluoroalkyl substances) are widely used as alternatives to long-chain PFASs. Long-chain PFASs become gradually regulated under REACH (EC No. 1907/2006) and other international regulations, due to having persistent, bioaccumulative and toxic properties and/or being toxic for reproduction. The increasingly used short-chain PFASs are assumed to have a low...

The feline anterior sartorius is a long strap-like muscle composed of short muscle fibers. Nerve branches that enter this muscle contain the axons of motor units whose constituent muscle fibers are distributed asymmetrically within the muscle. In the present study, twitch and tetanic isometric contractions were evoked by stimulating individual nerve branches while muscle force was recorded and ...